The present invention relates to a method and device for operating a motor vehicle braking system, including service or foot brake and a parking or hand brake, in which an audible signal is given after the vehicle is held in the stopped condition exclusively by application of the service brake for a given period of time.
It is customary for two different braking systems to be used to brake motor vehicles. For the most part, a braking system includes the so-called service or foot brake which as already indicated by the term is used during the vehicle's driving operation. This brake, which is essentially operated by pressurized media and usually is equipped with a power assist, is used to brake or decelerate the vehicle during operation, or to briefly maintain the vehicle in a stationary condition, for example, when a vehicle is stopped at a traffic light or the like. In addition, in certain driving situations, a motor vehicle can be braked by the drag torque of the engine. This type of service brake operation information is included here to facilitate understanding of the subject matter of the present invention.
In addition, a so-called parking brake is provided in each motor vehicle to secure the vehicle in a stationary condition for extended periods of time, preventing it from rolling away, or, even more importantly, to maintain braking of the vehicle and safeguard it against rolling away, while in the parked or engine off state.
Often the service brake is applied to brake a vehicle over extended periods to keep the vehicle stopped; however, this is not normal operational use of the service brake.
Consequently, dangerous situations can arise, e.g., when the driver of a vehicle briefly leaves the vehicle, e.g., in a traffic jam, after applying the service brake only and forgetting to activate the parking brake. In such situations the vehicle can then set itself in motion automatically.
Situations of this kind become more problematic in vehicles equipped with automatic proximity-control systems, which enable the vehicle to continue to move automatically after a vehicle in front of it moves, i.e., even in the absence of the driver of the vehicle, for as long as the vehicle, i.e., the engine and the electric system, are in operation.
Moreover, even when the vehicle is shut off, all too often one forgets to activate the parking brake thereby unintentionally enabling the vehicle to roll away from the parked position.
From the related art, one can infer a number of operating methods, including, in particular, automatic hand brakes. From the German 44 21 088 Al, a braking system for motor vehicles is known, which includes an automatic hand brake that can be applied automatically as a function of the vehicle's driving state. To accomplish this two parameters are monitored. On the one hand, the accelerator gas pedal must be in the neutral position and, on the other hand, the velocity must be less than two km/h. In this case, however, the controlled application of this automatic hand brake is used merely as a so-called starting aid, and does not contribute to achieving the objective described above.
German Patent 33 257 13 Al, (USSN) discloses a braking device which is operated as a conventional braking device integrated into a proximity-control method.
German Patent 195 23 111 Al, (USSN) discloses an automatic brake which is integrated into a proximity-control system.